SACCHARINE PRODUCTS. 7l 



where G = per cent of commercial glucose, a = direct polarization, S = per cent 

 of cane sugar. Express results in terms of commercial glucose polarizing 

 + 175 V. 



In substances which consist largely of invert sugar much more accurate 

 results are attained by polarizing at 87 C. in a water-jacketed tube an Inverted 

 half-normal solution of the sample (13 grams) prepared as directed under ** VI. 

 General Methods," page 41, with the following exceptions: After inversion, cool, 

 add a few drops of phenolphthalein and enough sodium hydroxid to neutralize; 

 discharge the pink color with a few drops of dilute hydrochloric acid, add from 

 5 to 10 cc of alumina cream, and make up to the mark and filter. Multiply by 

 2 the reading at 87 C. in the 200 rum tube; multiply this result by 100 and 

 divide by the factor 163 to express the glucose o in terms of glucose polarizing 

 +175 V. 



7. Reducing Sugars. Provisional. 



Determine either as dextrose or invert sugar as directed under " VI. Gen- 

 eral Methods," pages 42 and 49. 



8. Starch. Provisional. 



Measure gradually 25 cc of the 20 per cent solution or uniform mixture (1. 

 Preparation of Sample, (b), p. 64) into a hardened filter or gooch crucible, 

 or transfer by washing 5 grams of the finely powdered substance to the filter or 

 gooch, and allow the residue on the filter to become air dried. Extract with 5 

 successive portions of 10 cc of ether, then wash with 150 cc of 10 per cent 

 alcohol, and finally with 20 cc of strong alcohol. Transfer the residue to a 

 large flask and determine starch as directed under " VI. General Methods," 

 page 53. 



9. Ether Extract in Confectionery. Provisional. 



Pipette 25 cc of the 20 per cent mixture or solution (1. Preparation of Sam- 

 ple (b), p. 64) into a very thin, readily frangible, glass evaporating shell 

 (Hoffmeister's Schalchen), containing 5 to 7 grams of freshly ignited asbestos 

 fiber ; or, if impossible to obtain thus a uniform sample, weigh out 5 grams of 

 the mixed finely divided sample into a dish, and wash with water into the 

 asbestos in the evaporating shell, using, if necessary, a small portion of the 

 asbestos fiber on a stirring rod to transfer the last traces of the sample from 

 dish to shell. Dry to constant weight at 100 C., after which cool, wrap 

 loosely in smooth paper, and crush into rather small fragments between the 

 fingers, carefully transferring the pieces with the aid of a camel's-hair brush 

 to an extraction tube or a Schleicher and Schull cartridge for fat extraction. 

 A thin lead disk (bottle cap) may be substituted for the Schalchen. The disk 

 may then be cut into small pieces and placed in the extraction tube. Extract 

 with anhydrous ether or petroleum ether in a continuous-extraction apparatus 

 for at least twenty-five hours. Transfer to a tared flask, evaporate the ether, 

 dry in an oven at 100 C. to constant weight, and weigh. 



If petroleum ether is employed, it should be purified by fractional distillation 

 so that it boils between 45 and 60 C. and leaves absolutely no residue. 



Nearly all pure honeys are more or less dextro-rotatory at 87 C., according to the 

 amount of natural dextrin present. The reading at 87 C., however, rarely exceeds 20 V. 

 (26 grams per 100 cc), and then only in abnormal samples containing large quantities of 

 honeydew or other exudations than the nectar of flowers. To distinguish between ab- 

 normal honeydew honeys and honeys adulterated with glucose, see Konig (Zts. anal. 

 Chem., 1895, 34: 1) and Beckiuann (ibid., 1896, 35: 263). 



